One important conclusion that emerges from both GWAS and sequencing studies is that there are no common variants of large effect. To be precise, common variants that increase the chance of disease 1.3 fold or more are extremely unlikely to exist [9]. Similarly, for quantitative phenotypes, the expected effect sizes are less than 0.5% of phenotypic variance (for example, between 0.02 and 0.2% for each variant that contributes to variation in height [10]).
